WASHINGTON — If the range of possible Supreme Court rulings on gay marriage this month requires a scorecard, the potential confusion arising from those decisions may demand a manual.

It’s not as simple as whether gays and lesbians can marry or not, and whether they become eligible for federal benefits. The two decisions are likely to create new questions for couples in civil unions and those who move between states, as well as for employers.

As a result, what’s already a complex situation for many gay and lesbian couples could get more complicated, at least initially, says John Culhane, a law professor at Widener University’s Delaware campus and co-author of Same-Sex Legal Kit for Dummies.

“Obviously, we’re going to have to come up with a second edition pretty quickly,” Culhane says. “Whatever the court does, some things are going to change.”

A few of the potential decisions could make things easier or leave them unchanged, but those are among the more unlikely outcomes. The court could uphold California’s gay marriage ban, leaving the status quo there. It could declare a new right to marriage for all same-sex couples nationwide — an initial upheaval, but one offering long-term uniformity.

And the court could leave intact the Defense of Marriage Act (DOMA), which denies federal benefits to legally married gays and lesbians in 12 states and the District of Columbia that allow same-sex marriage. The law has created an uneven situation within and among states, but at least such a ruling wouldn’t require change.

But if DOMA’s benefits ban is struck down or the case is thrown out on technical grounds, both of which appear more likely, several unanswered questions would arise:

— What happens if legally married couples have moved to a state without same-sex marriage? The section of DOMA that protects those states from having to recognize marriages performed in other states would apply to state benefits, but what about federal benefits? That could be up to President Obama — and future court cases.

That’s because some federal agencies base marriage rights on where the license was issued, so the federal benefits would follow the couple; for others, however — including Social Security — it’s the current residence.

— What happens to couples in civil unions, from New Jersey to Hawaii, who currently receive virtually the same state benefits as those who are married?

Federal law does not recognize civil unions, so they wouldn’t automatically qualify for federal benefits. But Todd Solomon, an expert on domestic partner benefits at the law firm McDermott Will & Emery, says another legal fight could be expected.

New opportunities also would arise for gay and lesbian couples if the federal law denying benefits is struck down. Some are straightforward, such as being able to contest the last three years of federal tax returns. Others are more dramatic; for instance, they could move to a gay-marriage state because of the added attraction of federal benefits.

Getting divorced is another matter: If a same-sex married couple moves to a state that has not legalized gay marriage, they may have to move back to the first state to break the marriage apart, Branton says. A San Francisco attorney jokingly coined such a marriage “wedlocked.”